The kohbis petefls co



(No Model.)

A. D. SPENOER. TOOL FOR TRUING DYNAMO GOMMUTATORS. No. 430,094. Patented June 10, 1890.

-WITNEEEEE- INVENTIJFL- m: NW uuuu uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu c.

UNITED STATES PATENT IOFFICE.

ALLEN DUNTON SPENCER, OF BALTIMORE, MARYLAND, ASSIGNOR OF ONE- THIRD TO RICHARD M. WVALLACE, OF SAME PLACE.

TOOL FOR TRUING DYNAMO-COMMUTATORS.

SPECIFICATION forming part of Letters Patent No. 430,094, dated J' une 10, 1890.

Application filed February 1890. Serial No. 340,524. (No model.)

To all whmn it may concern:

Be it known that I, ALLEN DUNTON SPEN- CER, of the city of Baltimore, and State of Maryland, have invented certain Improve- 5 ments in Tools for Truing Dynamo-Commutators, of which the following is a specification.

This invention relates to certain improvements in a tool Whereby the faces of dynamo- :o commutators and other rotative cylindrical objects which have become WOI'Il may be trued or brought to an accurate cylindrical shape while the same is in motion, as will hereinafter fully appeal'.

:5 The said invention consists in a segmental toothed block having suitable handles, whereby the same may be held to the surface to be repaired.

In the further description of the said in- 'o vention which follows reference is made to denoted by a, is serrated or toothed after the manner of afile, and its curvature is made as nearly as possible to correspond with the circumference of the Object to be trued. The

back Z) of the block is flat, and to it is secured 3 5 by means of screws c a bar d, having the handles c at its ends. The length of the block A is preferably the sane as that of the face of the commutator or obj ect to be filed.

Commutators, if not properly watched and 4o attended to, become grooved and fiattened by the action of the brushes, and they are generally taken from the machine and turned, so as to be again true, in a lathe. This operation of course renders the dynamo of no use for the time, and the truing operation is expensive.

The commutator may be put in complete order by holding with both hands the device described against its cylindrical surface until the irregular projections on the same are removed.

The commutator is shown in dotted lines in Fig. 1 and marked O. One of the handles c may be thrown up, as shown in dotted lines in Fig. 1, if desired.

I claim as my invention- A tool for the purpose described, which consists of a hardened steel block with a segnental toothed face, combined With a bar secured transversely of the back of the block, and ahandle at each end of the bar, substantially as and for the purpose specified.

ALLEN DUNTON SPENOER.

VVitnesses:

WM. T. I-IOWARD, DANL. FISHER. 

